Zinc bromide (209 mg) was added to a solution of tert-butyl(2R)-2-{[{[5-bromo-1-(3-methoxypropyl)indol-3-yl]methyl}(cyclopropyl)amino]carbonyl}morpholin-4-carboxylate (a compound of Reference Example 128, 200 mg) in 1,2-dichloroethane (12 ml) and the mixture was stirred at 40° C. for 3 hours. The reaction mixture was poured into a saturated aqueous solution of sodium bicarbonate and extracted with chloroform. The organic layer was washed with water and saturated brine, dried over magnesium sulfate and concentrated in vacuo. The resulted residue was purified with a silica gel column chromatography (eluting solvent: chloroform/methanol=98/2 to 93/7) to give (2R)—N-{[5-bromo-1-(3-methoxypropyl)indol-3-yl]methyl}-N-cyclopropylmorpholin-2-carboxamide (117 mg) as a colorless oil.
